<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.7.14/dist/vue.js"></script>
</head>
<style>
    button{
        height: 50px;
        width: 50px;
        font-size: 20px;
        border: 10px black;
    }
</style>
<!-- v-on:click v-on:mouseenter -->
<!-- @ -->
<body>
    <div id="app">
        <button @Click="count++">+</button>
        {{count}}
        <button @mouseenter="count--">-</button>
    </div>
</body>
<script>
   const app=new Vue({
    el:'#app',
    data:{
    count:1
    }
   })
</script>
</html>